When 1D response analysis fails: application of Earthquake HVSR in Site-Specific Amplification Estimation

2020 ◽  
Author(s):  
Chuanbin Zhu ◽  
Marco Pilz ◽  
Fabrice Cotton
Keyword(s):  
Transfer Function ◽  
Resonant Frequency ◽  
Goodness Of Fit ◽  
Spectral Ratio ◽  
Spectral Shape ◽  
Response Analysis ◽  
Specific Information ◽  
S Wave ◽  
Site Specific ◽  
Empirical Correction

<p>Ground response analyses (GRA) model the vertical propagation of SH waves through flat-layered media (1DSH) and are widely carried out to evaluate local site effects in practice. Horizontal-to-vertical spectral ratio (HVSR) technique is a cost-effective approach to extract certain site-specific information, e.g., site resonant frequency, but HVSR values cannot be directly used to approximate the level of S-wave amplification. Motivated by the work of Kawase et al. (2019), we propose a procedure to correct earthquake HVSR amplitude for direct amplification estimation. The empirical correction, in essence, compensates HVSR by generic vertical amplifications grouped by vertical fundamental resonant frequency (f<sub>0v</sub>) and 30 m average shear-wave velocity (V<sub>S30</sub>) via k-mean clustering. In this investigation, we evaluate the effectiveness of the corrected HVSR in approximating observed amplification in comparison with 1DSH modelling. To the end, we select a total of 90 KiK-net surface-downhole recording sites which are found to have no velocity contrasts below downhole sensor and thus of which surface-to-borehole spectral ratio (SBSR) can be taken as its empirical transfer function (ETF). 1DSH-based theoretical transfer function (TFF) is computed in the linear domain considering the uncertainty in V<sub>S</sub> profile through randomization. Five goodness-of-fit metrics are adopted to gauge the closeness between observed (ETF) and predicted (i.e., TTF and corrected HVSR) amplifications in both amplitude and spectral shape. The major finding of this study is that the empirical correction procedure to HVSR is highly effective, and the corrected HVSR has a “good match” in both spectral shape (Pearson’s r > 0.6) and amplitude (Index of agreement d > 0.6) at 74% of the investigated sites, as opposed to 17% for 1DSH modelling. In addition, the HVSR-based empirical correction does not need a site model and thus has great potentials in site-specific seismic hazard assessments.</p>

scholarly journals How well can we predict earthquake site response so far? Site-specific approaches

2022 ◽  
pp. 875529302110608
Author(s):  
Chuanbin Zhu ◽  
Fabrice Cotton ◽  
Hiroshi Kawase ◽  
Annabel Haendel ◽  
Marco Pilz ◽  
...  
Keyword(s):  
Site Effects ◽  
Seismic Waves ◽  
Site Response ◽  
Spectral Ratio ◽  
Response Analysis ◽  
Ground Response Analysis ◽  
Site Specific ◽  
Quarter Wavelength ◽  
High Level ◽  
Surface Geology

Earthquake site responses or site effects are the modifications of surface geology to seismic waves. How well can we predict the site effects (average over many earthquakes) at individual sites so far? To address this question, we tested and compared the effectiveness of different estimation techniques in predicting the outcrop Fourier site responses separated using the general inversion technique (GIT) from recordings. Techniques being evaluated are (a) the empirical correction to the horizontal-to-vertical spectral ratio of earthquakes (c-HVSR), (b) one-dimensional ground response analysis (GRA), and (c) the square-root-impedance (SRI) method (also called the quarter-wavelength approach). Our results show that c-HVSR can capture significantly more site-specific features in site responses than both GRA and SRI in the aggregate, especially at relatively high frequencies. c-HVSR achieves a “good match” in spectral shape at ∼80%–90% of 145 testing sites, whereas GRA and SRI fail at most sites. GRA and SRI results have a high level of parametric and/or modeling errors which can be constrained, to some extent, by collecting on-site recordings.

Site effect evaluation using spectral ratios with only one station

1993 ◽  
Vol 83 (5) ◽  
pp. 1574-1594
Author(s):  
Javier Lermo ◽  
Francisco J. Chávez-García
Keyword(s):  
Transfer Function ◽  
Rayleigh Waves ◽  
Site Effects ◽  
Spectral Ratio ◽  
Site Effect ◽  
Reference Station ◽  
Effect Evaluation ◽  
Spectral Ratios ◽  
S Wave ◽  
Dominant Period

Abstract The spectral ratio technique is a common useful way to estimate empirical transfer function to evaluates site effects in regions of moderate to high seismicity. The purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station. The technique, originally proposed by Nakamura to analyze Rayleigh waves in the microtremor records, is presented briefly and it is discussed why it may be applicable to study the intense S-wave part in earthquake records. Results are presented for three different cities in Mexico: Oaxaca, Oax., Acapulco, Gro., and Mexico City. These cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city. Each time we compare the results of Nakamura's technique with standard spectral ratios. In all three cases the results are very encouraging. We conclude that, if site effects are caused by simple geology, a first estimate of dominant period and local amplification level can be obtained using records of only one station.

scholarly journals Applicability of On-Site P-Wave Earthquake Early Warning to Seismic Data Observed During the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan

2021 ◽  
Vol 9 ◽  
Author(s):  
Seiji Tsuno
Keyword(s):  
Seismic Data ◽  
Time Window ◽  
Seismic Station ◽  
Tohoku Earthquake ◽  
Spectral Ratio ◽  
P Wave ◽  
S Wave ◽  
Site Specific ◽  
Source Effects ◽  
The Pacific

In this study, the on-site P-wave earthquake early warning (EEW) based on the site-specific spectral ratio of S-wave to P-wave to efficiently incorporate the site characteristics, which can potentially issue the earthquake warning by the time of Ts-p, was developed. The spectral ratio of S-wave to P-wave that are related to the source effects, the path effects, and the site effects are significantly affected by the site effects contrast to the source effects and the path effects in practical. At first, the on-site P-wave EEW method which multiplies a site-specific spectral ratio of S-wave to P-wave prepared in advance by P-wave observed in the real-time at seismic stations is applied to seismic data for moderate-sized earthquakes with a magnitude (Mj) of 5.0–6.0, occurred in the eastern Japan, observed at both the sedimentary basin site and the rock site. As a result, this method predicted well the observed S-wave in the single indicator of SI within the logarithmic standard deviation of 0.25 as well as in the frequency of more than 0.5 Hz. It is, also, confirmed that the site-specific spectral ratio of S-wave to P-wave at a seismic station was stably retrieved from 20 data samples at least. To investigate the applicability of this method to earthquake ground motions induced by a large-scaled earthquake, finally, this method is applied to seismic data during the 2011 off the Pacific coast of Tohoku earthquake, Japan (Mw 9.0). The prediction of S-wave using a time-window of 10 s after P-wave arrived, could not reproduce the observation with the underestimation; however, the prediction of S-wave using a time-window of more than 20 s containing P-wave propagated from an area generating strong motions in the fault, could reproduce the observation. Even in the case of the large-scaled earthquake, the on-site P-wave EEW method based on the site-specific spectral ratio of S-wave to P-wave at a seismic station availably works by using the gradually increasing time-windows after P-wave arrived in the single indicator of SI as well as in the frequency content, avoiding the mixture of S-wave into a part of P-wave.

Vibration Analysis of Single Walled Boron Nitride Nanotube Based Nanoresonators

2012 ◽  
Vol 3 (3) ◽  
Author(s):  
Mitesh B. Panchal ◽  
S. H. Upadhyay ◽  
S. P. Harsha
Keyword(s):  
Boron Nitride ◽  
Resonant Frequency ◽  
Continuum Mechanics ◽  
Boron Nitride Nanotubes ◽  
Response Analysis ◽  
Published Data ◽  
Boron Nitride Nanotube ◽  
Mass Sensor ◽  
Nanomechanical Resonators ◽  
Mass Sensitivity

In this paper, the vibration response analysis of single walled boron nitride nanotubes (SWBNNTs) treated as thin walled tube has been done using finite element method (FEM). The resonant frequencies of fixed-free SWBNNTs have been investigated. The analysis explores the resonant frequency variations as well as the resonant frequency shift of the SWBNNTs caused by the changes in size of BNNTs in terms of length as well as the attached masses. The performance of cantilevered SWBNNT mass sensor is also analyzed based on continuum mechanics approach and compared with the published data of single walled carbon nanotube (SWCNT) for fixed-free configuration as a mass sensor. As a systematic analysis approach, the simulation results based on FEM are compared with the continuum mechanics based analytical approach and are found to be in good agreement. It is also found that the BNNT cantilever biosensor has better response and sensitivity compared to the CNT as a counterpart. Also, the results indicate that the mass sensitivity of cantilevered boron nitride nanotube nanomechanical resonators can reach 10−23 g and the mass sensitivity increases when smaller size nanomechanical resonators are used in mass sensors.

scholarly journals Malarial parasites as geographical markers in migratory birds?

2006 ◽  
Vol 2 (2) ◽  
pp. 213-216 ◽  
Author(s):  
Sylvia M Fallon ◽  
Robert C Fleischer ◽  
Gary R Graves
Keyword(s):  
North America ◽  
Migratory Birds ◽  
Wide Distribution ◽  
Specific Information ◽  
Population Movements ◽  
Site Specific ◽  
Dendroica Caerulescens ◽  
Bird Populations ◽  
Breeding Populations ◽  
Wintering Range

We tested the hypothesis that malarial parasites ( Plasmodium and Haemoproteus ) of black-throated blue warblers ( Dendroica caerulescens ) provide sufficient geographical signal to track population movements between the warbler's breeding and wintering habitats in North America. Our results from 1083 warblers sampled across the species' breeding range indicate that parasite lineages are geographically widespread and do not provide site-specific information. The wide distribution of malarial parasites probably reflects postnatal dispersal of their hosts as well as mixing of breeding populations on the wintering range. When compared to geographically structured parasites of sedentary Caribbean songbirds, patterns of malarial infections in black-throated blue warblers suggest that host–malaria dynamics of migratory and sedentary bird populations may be subject to contrasting selection pressures.

Value of site-specific information for the design of offshore wind farms

2019 ◽  
Author(s):  
Jorge Mendoza Espinosa ◽  
Jochen Köhler
Keyword(s):  
Safety Margin ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Specific Information ◽  
Offshore Wind Farms ◽  
Site Specific ◽  
A Value ◽  
Probabilistic Characterization ◽  
Clear Guideline

<p>Monopiles are the most common offshore wind turbine support structures. They are to be designed so that resonance with the rotor-passing excitation is avoided. However, the estimation of the eigenfrequencies is strongly influenced by the soil-structure interaction, whose characterization with prior information is associated with large uncertainties. No clear guideline is given regarding the safety margin to be left between the structure first natural frequency and the excitation regions. In this paper, the expected consequences of leaving a certain margin are studied and quantified. The decisions regarding the investment in site-specific characterization are coupled into the decision scenario by means of a value of information analysis. The results provide insight on the efficient allocation of resources at the design point in time and the sensitivity of the decisions regarding the probabilistic characterization of the design scenario.</p>

Approximate Analytical Expressions of the Fundamental Peak Frequency and the Amplification Factor of S-wave Transfer Function in a Viscoelastic Layered Model

2018 ◽  
Vol 176 (4) ◽  
pp. 1433-1443
Author(s):  
Tran Thanh Tuan ◽  
Pham Chi Vinh ◽  
Abdelkrim Aoudia ◽  
Truong Thi Thuy Dung ◽  
Daniel Manu-Marfo
Keyword(s):  
Transfer Function ◽  
Amplification Factor ◽  
Peak Frequency ◽  
S Wave ◽  
Layered Model ◽  
Analytical Expressions

scholarly journals THE URBIS PROJECT: IDENTIFICATION AND CHARACTERIZATION OF POTENTIAL URBAN DEVELOPMENT AREAS AS A WEB-BASED SERVICE

2016 ◽  
Vol XLI-B4 ◽  
pp. 227-233
Author(s):  
Nina Manzke ◽  
Martin Kada ◽  
Thomas Kastler ◽  
Shaojuan Xu ◽  
Norbert de Lange ◽  
...  
Keyword(s):  
Urban Areas ◽  
Landscape Fragmentation ◽  
Urban Land ◽  
End Users ◽  
Information Services ◽  
Urban Land Use ◽  
Specific Information ◽  
Remotely Sensed Data ◽  
Web Based ◽  
Site Specific

Urban sprawl and the related landscape fragmentation is a Europe-wide challenge in the context of sustainable urban planning. The URBan land recycling Information services for Sustainable cities (URBIS) project aims for the development, implementation, and validation of web-based information services for urban vacant land in European functional urban areas in order to provide end-users with site specific characteristics and to facilitate the identification and evaluation of potential development areas. The URBIS services are developed based on open geospatial data. In particular, the Copernicus Urban Atlas thematic layers serve as the main data source for an initial inventory of sites. In combination with remotely sensed data like SPOT5 images and ancillary datasets like OpenStreetMap, detailed site specific information is extracted. Services are defined for three main categories: i) baseline services, which comprise an initial inventory and typology of urban land, ii) update services, which provide a regular inventory update as well as an analysis of urban land use dynamics and changes, and iii) thematic services, which deliver specific information tailored to end-users' needs.

Quantitative risk assessment in the Water Safety Plan: case studies from drinking water practice

2009 ◽  
Vol 9 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Gertjan Medema ◽  
Patrick Smeets
Keyword(s):  
Drinking Water ◽  
Case Studies ◽  
Level Of Detail ◽  
Specific Information ◽  
Water Safety ◽  
Site Specific ◽  
Safety Plan ◽  
Water Safety Plan ◽  
System Assessment

System assessment is the part of the Water Safety Plan that evaluates whether a water supply system is capable of producing drinking water that meets the health-based targets. System assessment can be done at increasing level of detail, requiring more site specific information as the level of detail increases. Four case studies are presented with increasing level of detail, showing the type of information that is required for each of these levels and how each level informs risk management. The first case study shows how a system assessment can be performed without other site specific information than the type of source water and the type of treatment processes. The required data for the system assessment are collected from the large body of literature available. The second case study uses site specific microbial indicator data. The third study uses pathogen data and the fourth case study combines data on pathogens, microbial indicators and process parameters. The case studies show that the level of detail required largely depends on the risk management question.

Regional propagation characteristics and source parameters of earthquakes in northeastern North America

1994 ◽  
Vol 84 (1) ◽  
pp. 1-15 ◽  
Author(s):  
John Boatwright
Keyword(s):  
Site Response ◽  
Source Parameters ◽  
Low Frequency ◽  
Response Spectra ◽  
Spectral Shape ◽  
Propagation Characteristics ◽  
S Wave ◽  
Data Set ◽  
Wave Trains ◽  
Source Site

Abstract The vertical components of the S wave trains recorded on the Eastern Canadian Telemetered Network (ECTN) from 1980 through 1990 have been spectrally analyzed for source, site, and propagation characteristics. The data set comprises some 1033 recordings of 97 earthquakes whose magnitudes range from M ≈ 3 to 6. The epicentral distances range from 15 to 1000 km, with most of the data set recorded at distances from 200 to 800 km. The recorded S wave trains contain the phases S, SmS, Sn, and Lg and are sampled using windows that increase with distance; the acceleration spectra were analyzed from 1.0 to 10 Hz. To separate the source, site, and propagation characteristics, an inversion for the earthquake corner frequencies, low-frequency levels, and average attenuation parameters is alternated with a regression of residuals onto the set of stations and a grid of 14 distances ranging from 25 to 1000 km. The iteration between these two parts of the inversion converges in about 60 steps. The average attenuation parameters obtained from the inversion were Q = 1997 ± 10 and γ = 0.998 ± 0.003. The most pronounced variation from this average attenuation is a marked deamplification of more than a factor of 2 at 63 km and 2 Hz, which shallows with increasing frequency and increasing distance out to 200 km. The site-response spectra obtained for the ECTN stations are generally flat. The source spectral shape assumed in this inversion provides an adequate spectral model for the smaller events (Mo &lt; 3 × 1021 dyne-cm) in the data set, whose Brune stress drops range from 5 to 150 bars. For the five events in the data set with Mo ≧ 1023 dyne-cm, however, the source spectra obtained by regressing the residuals suggest that an ω2 spectrum is an inadequate model for the spectral shape. In particular, the corner frequencies for most of these large events appear to be split, so that the spectra exhibit an intermediate behavior (where |ü(ω)| is roughly proportional to ω).

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